freebsd/sys/kern/link_aout.c

/*-
 * Copyright (c) 1997-2000 Doug Rabson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD$
 */

#ifdef __i386__

#define FREEBSD_AOUT	1

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/namei.h>
#include <sys/fcntl.h>
#include <sys/vnode.h>
#include <sys/linker.h>


#include "linker_if.h"

#ifndef __ELF__
#include <vm/vm.h>
#include <vm/pmap.h>
#include <machine/vmparam.h>
#endif

#include <a.out.h>
#include <link.h>

typedef struct aout_file {
    struct linker_file	lf;		/* Common fields */
    int			preloaded;	/* Was this pre-loader */
    char*		address;	/* Load address */
    struct _dynamic*	dynamic;	/* Symbol table etc. */
} *aout_file_t;

static int		link_aout_link_preload(linker_class_t lc,
					       const char* modname, linker_file_t*);
static int		link_aout_link_preload_finish(linker_file_t);

static int		link_aout_load_file(linker_class_t lc, const char*, linker_file_t*);
static int		link_aout_lookup_symbol(linker_file_t, const char*,
						c_linker_sym_t*);
static int		link_aout_symbol_values(linker_file_t file, c_linker_sym_t sym,
						linker_symval_t* symval);
static int		link_aout_search_symbol(linker_file_t lf, caddr_t value,
						c_linker_sym_t* sym, long* diffp);
static void		link_aout_unload_file(linker_file_t);
static void		link_aout_unload_preload(linker_file_t);
static int		link_aout_lookup_set(linker_file_t, const char*,
					     void ***, void ***, int*);

static kobj_method_t link_aout_methods[] = {
    KOBJMETHOD(linker_lookup_symbol,	link_aout_lookup_symbol),
    KOBJMETHOD(linker_symbol_values,	link_aout_symbol_values),
    KOBJMETHOD(linker_search_symbol,	link_aout_search_symbol),
    KOBJMETHOD(linker_unload,		link_aout_unload_file),
    KOBJMETHOD(linker_load_file,	link_aout_load_file),
    KOBJMETHOD(linker_link_preload,	link_aout_link_preload),
    KOBJMETHOD(linker_link_preload_finish, link_aout_link_preload_finish),
    KOBJMETHOD(linker_lookup_set,	link_aout_lookup_set),
    { 0, 0 }
};

static struct linker_class link_aout_class = {
    "a.out", link_aout_methods, sizeof(struct aout_file)
};

static int		relocate_file(aout_file_t af);

/*
 * The kernel symbol table starts here.
 */
extern struct _dynamic __DYNAMIC;

static void
link_aout_init(void* arg)
{
#ifndef __ELF__
    struct _dynamic* dp = &__DYNAMIC;
#endif

    linker_add_class(&link_aout_class);

#ifndef __ELF__
    if (dp) {
	aout_file_t af;

	linker_kernel_file =
	    linker_make_file(kernelname, &link_aout_class);
	if (linker_kernel_file == NULL)
	    panic("link_aout_init: Can't create linker structures for kernel");
	af = (aout_file_t) linker_kernel_file;
	af->address = 0;
	af->dynamic = dp;
	linker_kernel_file->address = (caddr_t) KERNBASE;
	linker_kernel_file->size = -(long)linker_kernel_file->address;
    }
#endif
}

SYSINIT(link_aout, SI_SUB_KLD, SI_ORDER_THIRD, link_aout_init, 0);

static int
link_aout_link_preload(linker_class_t lc,
		       const char* filename, linker_file_t* result)
{
    caddr_t		modptr, baseptr;
    char		*type;
    struct exec		*ehdr;
    aout_file_t		af;
    linker_file_t	lf;
    
    /* Look to see if we have the module preloaded. */
    modptr = preload_search_by_name(filename);
    if (modptr == NULL)
	return ENOENT;

    if (((type = (char *)preload_search_info(modptr, MODINFO_TYPE)) == NULL) ||
	strcmp(type, "a.out module") ||
	((baseptr = preload_search_info(modptr, MODINFO_ADDR)) == NULL) ||
	((ehdr = (struct exec *)preload_search_info(modptr, MODINFO_METADATA | MODINFOMD_AOUTEXEC)) == NULL))
	return(0);			/* we can't handle this */

    /* Register with kld */
    lf = linker_make_file(filename, &link_aout_class);
    if (lf == NULL) {
	return(ENOMEM);
    }
    af = (aout_file_t) lf;

    /* Looks like we can handle this one */
    filename = preload_search_info(modptr, MODINFO_NAME);
    af->preloaded = 1;
    af->address = baseptr;

    /* Assume _DYNAMIC is the first data item. */
    af->dynamic = (struct _dynamic*)(af->address + ehdr->a_text);
    if (af->dynamic->d_version != LD_VERSION_BSD) {
	linker_file_unload(lf);
	return(0);			/* we can't handle this */
    }
    af->dynamic->d_un.d_sdt = (struct section_dispatch_table *)
	((char *)af->dynamic->d_un.d_sdt + (vm_offset_t)af->address);

    lf->address = af->address;
    lf->size = ehdr->a_text + ehdr->a_data + ehdr->a_bss;
    *result = lf;
    return(0);
}

static int
link_aout_link_preload_finish(linker_file_t lf)
{
    aout_file_t af;
    int error;

    af = (aout_file_t) lf;
    error = relocate_file(af);
    if (error) {
	linker_file_unload(lf);
	return(error);
    }
    return(0);
}

static int
link_aout_load_file(linker_class_t lc, const char* filename, linker_file_t* result)
{
    struct nameidata nd;
    struct thread *td = curthread;	/* XXX */
    int error = 0;
    int resid, flags;
    struct exec header;
    aout_file_t af;
    linker_file_t lf = 0;

    NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
    flags = FREAD;
    error = vn_open(&nd, &flags, 0);
    if (error)
	return error;
    NDFREE(&nd, NDF_ONLY_PNBUF);

    /*
     * Read the a.out header from the file.
     */
    error = vn_rdwr(UIO_READ, nd.ni_vp, (void*) &header, sizeof header, 0,
		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, &resid, td);
    if (error)
	goto out;

    if (N_BADMAG(header) || !(N_GETFLAG(header) & EX_DYNAMIC))
	goto out;

    /*
     * We have an a.out file, so make some space to read it in.
     */
    lf = linker_make_file(filename, &link_aout_class);
    if (lf == NULL) {
	error = ENOMEM;
	goto out;
    }

    af = (aout_file_t) lf;
    af->address = malloc(header.a_text + header.a_data + header.a_bss,
			 M_LINKER, M_WAITOK);
    
    /*
     * Read the text and data sections and zero the bss.
     */
    error = vn_rdwr(UIO_READ, nd.ni_vp, (void*) af->address,
		    header.a_text + header.a_data, 0,
		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, &resid, td);
    if (error)
	goto out;
    bzero(af->address + header.a_text + header.a_data, header.a_bss);

    /*
     * Assume _DYNAMIC is the first data item.
     */
    af->dynamic = (struct _dynamic*) (af->address + header.a_text);
    if (af->dynamic->d_version != LD_VERSION_BSD) {
	error = ENOEXEC;
	goto out;
    }
    af->dynamic->d_un.d_sdt = (struct section_dispatch_table *)
	((char *)af->dynamic->d_un.d_sdt + (vm_offset_t)af->address);

    lf->address = af->address;
    lf->size = header.a_text + header.a_data + header.a_bss;

    error = linker_load_dependencies(lf);
    if (error)
	goto out;
    error = relocate_file(af);
    if (error)
	goto out;

    *result = lf;

out:
    if (error && lf)
	linker_file_unload(lf);
    VOP_UNLOCK(nd.ni_vp, 0, td);
    vn_close(nd.ni_vp, FREAD, td->td_ucred, td);

    return error;
}

static void
link_aout_unload_file(linker_file_t file)
{
    aout_file_t af = (aout_file_t) file;

    if (af->preloaded) {
	link_aout_unload_preload(file);
	return;
    }

    if (af->address)
	free(af->address, M_LINKER);
}

static void
link_aout_unload_preload(linker_file_t file)
{
    if (file->filename)
	preload_delete_name(file->filename);
}

/*
 * XXX i386 dependant.
 */
static long
read_relocation(struct relocation_info* r, char* addr)
{
    int length = r->r_length;

    if (length == 0)
	return *(u_char*) addr;
    else if (length == 1)
	return *(u_short*) addr;
    else if (length == 2)
	return *(u_int*) addr;
    else
	printf("link_aout: unsupported relocation size %d\n", r->r_length);
    return 0;
}

static void
write_relocation(struct relocation_info* r, char* addr, long value)
{
    int length = r->r_length;

    if (length == 0)
	*(u_char*) addr = value;
    else if (length == 1)
	*(u_short*) addr = value;
    else if (length == 2)
	*(u_int*) addr = value;
    else
	printf("link_aout: unsupported relocation size %d\n", r->r_length);
}

#define AOUT_RELOC(af, type, off) (type*) ((af)->address + (off))

static int
relocate_file(aout_file_t af)
{
    struct relocation_info* rel;
    struct relocation_info* erel;
    struct relocation_info* r;
    struct nzlist* symbolbase;
    char* stringbase;
    struct nzlist* np;
    char* sym;
    long relocation;

    rel = AOUT_RELOC(af, struct relocation_info, LD_REL(af->dynamic));
    erel = AOUT_RELOC(af, struct relocation_info,
		      LD_REL(af->dynamic) + LD_RELSZ(af->dynamic));
    symbolbase = AOUT_RELOC(af, struct nzlist, LD_SYMBOL(af->dynamic));
    stringbase = AOUT_RELOC(af, char, LD_STRINGS(af->dynamic));

    for (r = rel; r < erel; r++) {
	char* addr;

	if (r->r_address == 0)
	    break;

	addr = AOUT_RELOC(af, char, r->r_address);
	if (r->r_extern) {
	    np = &symbolbase[r->r_symbolnum];
	    sym = &stringbase[np->nz_strx];

	    if (sym[0] != '_') {
		printf("link_aout: bad symbol name %s\n", sym);
		relocation = 0;
	    } else
		relocation = (intptr_t)
		    linker_file_lookup_symbol(&af->lf, sym + 1,
					      np->nz_type != (N_SETV+N_EXT));
	    if (!relocation) {
		printf("link_aout: symbol %s not found\n", sym);
		return ENOENT;
	    }
	    
	    relocation += read_relocation(r, addr);

	    if (r->r_jmptable) {
		printf("link_aout: can't cope with jump table relocations\n");
		continue;
	    }

	    if (r->r_pcrel)
		relocation -= (intptr_t) af->address;

	    if (r->r_copy) {
		printf("link_aout: can't cope with copy relocations\n");
		continue;
	    }
	    
	    write_relocation(r, addr, relocation);
	} else {
	    write_relocation(r, addr,
			     (intptr_t)(read_relocation(r, addr) + af->address));
	}
	
    }

    return 0;
}

static long
symbol_hash_value(aout_file_t af, const char* name)
{
    long hashval;
    const char* p;

    hashval = '_';		/* fake a starting '_' for C symbols */
    for (p = name; *p; p++)
	hashval = (hashval << 1) + *p;

    return (hashval & 0x7fffffff) % LD_BUCKETS(af->dynamic);
}

int
link_aout_lookup_symbol(linker_file_t file, const char* name,
			c_linker_sym_t* sym)
{
    aout_file_t af = (aout_file_t) file;
    long hashval;
    struct rrs_hash* hashbase;
    struct nzlist* symbolbase;
    char* stringbase;
    struct rrs_hash* hp;
    struct nzlist* np;
    char* cp;

    if (LD_BUCKETS(af->dynamic) == 0)
	return 0;

    hashbase = AOUT_RELOC(af, struct rrs_hash, LD_HASH(af->dynamic));
    symbolbase = AOUT_RELOC(af, struct nzlist, LD_SYMBOL(af->dynamic));
    stringbase = AOUT_RELOC(af, char, LD_STRINGS(af->dynamic));

restart:
    hashval = symbol_hash_value(af, name);
    hp = &hashbase[hashval];
    if (hp->rh_symbolnum == -1)
	return ENOENT;

    while (hp) {
	np = (struct nzlist *) &symbolbase[hp->rh_symbolnum];
	cp = stringbase + np->nz_strx;
	/*
	 * Note: we fake the leading '_' for C symbols.
	 */
	if (cp[0] == '_' && !strcmp(cp + 1, name))
	    break;

	if (hp->rh_next == 0)
	    hp = NULL;
	else
	    hp = &hashbase[hp->rh_next];
    }

    if (hp == NULL)
	/*
	 * Not found.
	 */
	return ENOENT;

    /*
     * Check for an aliased symbol, whatever that is.
     */
    if (np->nz_type == N_INDR+N_EXT) {
	name = stringbase + (++np)->nz_strx + 1; /* +1 for '_' */
	goto restart;
    }

    /*
     * Check this is an actual definition of the symbol.
     */
    if (np->nz_value == 0)
	return ENOENT;

    if (np->nz_type == N_UNDF+N_EXT && np->nz_value != 0) {
	if (np->nz_other == AUX_FUNC)
	    /* weak function */
	    return ENOENT;
    }

    *sym = (linker_sym_t) np;

    return 0;
}


static int
link_aout_symbol_values(linker_file_t file, c_linker_sym_t sym,
			linker_symval_t* symval)
{
    aout_file_t af = (aout_file_t) file;
    const struct nzlist* np = (const struct nzlist*) sym;
    char* stringbase;
    long numsym = LD_STABSZ(af->dynamic) / sizeof(struct nzlist);
    struct nzlist *symbase;

    /* Is it one of ours?  It could be another module... */
    symbase = AOUT_RELOC(af, struct nzlist, LD_SYMBOL(af->dynamic));
    if (np < symbase)
	return ENOENT;
    if ((np - symbase) > numsym)
	return ENOENT;

    stringbase = AOUT_RELOC(af, char, LD_STRINGS(af->dynamic));

    symval->name = stringbase + np->nz_strx + 1; /* +1 for '_' */
    if (np->nz_type == N_UNDF+N_EXT && np->nz_value != 0) {
	symval->value = 0;
	symval->size = np->nz_value;
    } else {
	symval->value = AOUT_RELOC(af, char, np->nz_value);
	symval->size = np->nz_size;
    }
    return 0;
}

static int
link_aout_search_symbol(linker_file_t lf, caddr_t value,
			c_linker_sym_t* sym, long* diffp)
{
	aout_file_t af = (aout_file_t) lf;
	u_long off = (uintptr_t) (void *) value;
	u_long diff = off;
	u_long sp_nz_value;
	struct nzlist* sp;
	struct nzlist* ep;
	struct nzlist* best = 0;

	for (sp = AOUT_RELOC(af, struct nzlist, LD_SYMBOL(af->dynamic)),
		 ep = (struct nzlist *) ((caddr_t) sp + LD_STABSZ(af->dynamic));
	     sp < ep; sp++) {
		if (sp->nz_name == 0)
			continue;
		sp_nz_value = sp->nz_value + (uintptr_t) (void *) af->address;
		if (off >= sp_nz_value) {
			if (off - sp_nz_value < diff) {
				diff = off - sp_nz_value;
				best = sp;
				if (diff == 0)
					break;
			} else if (off - sp_nz_value == diff) {
				best = sp;
			}
		}
	}
	if (best == 0)
		*diffp = off;
	else
		*diffp = diff;
	*sym = (linker_sym_t) best;

	return 0;
}

/*
 * Look up a linker set on an a.out + gnu LD system.
 */
struct generic_linker_set {
	int	ls_length;
	void	*ls_items[1];
};
static int
link_aout_lookup_set(linker_file_t lf, const char *name,
		     void ***startp, void ***stopp, int *countp)
{
	c_linker_sym_t sym;
	linker_symval_t symval;
	void **start, **stop;
	int error, count;
	struct generic_linker_set *setp;

	error = link_aout_lookup_symbol(lf, name, &sym);
	if (error)
		return error;
	link_aout_symbol_values(lf, sym, &symval);
	if (symval.value == 0)
		return ESRCH;
	setp = (struct generic_linker_set *)symval.value;
	count = setp->ls_length;
	start = &setp->ls_items[0];
	stop = &setp->ls_items[count];
	if (startp)
		*startp = start;
	if (stopp)
		*stopp = stop;
	if (countp)
		*countp = count;
	return 0;
}

#endif /* __i386__ */